URL blocking

February 1, 2007 at 11:28 am | Posted in Ramblings | 8 Comments

Sometimes you need to download a useful program from the internet, say Google Talk, and install it on your PC at work. And suddenly you are confronted with company policies about certain url’s that are blocked. I very well understand that you shouldn’t visit the Playboy site during working hours, but sometimes these url filters really become annoying. Of course I could have downloaded Google Talk from a different site that wasn’t filtered, but there is another straightforward approach:

  • Just do a ping traceroute to the site you want to visit. I used this website to do that on-line.
  • The Google IP address I got was:
  • I entered in my browser and happily downloaded Google Talk.

Disclaimer: this approach is probably not going to work if your company uses a somewhat smarter url blocking program than mine. Secondly: I’m not encouraging anyone to visit sites that your company probably has blocked for a very good reason.


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  1. Maurits,

    Maybe you shouldn’t work at that lightbulb factory 😉
    We can use some people over here in Veldhoven 😉


  2. Hey! I didn’t expect you on my blog. Anyhow, I might be in Veldhoven before you know, maybe starting 1st of March.

  3. Well, I’m pretty sure that URL block was there explicitely to keep you from downloading Instant Messengers, which are usually frowned upon if not explicitly forbidden in corporate environments.

    Apart from that, doing a traceroute just to resolve an IP is a bit overcomplicated, and your magic trick won’t work on sites hosted with shared IPs. And there are alot of them.

  4. “Well, I’m pretty sure that URL block was there explicitely to keep you from downloading Instant Messengers, which are usually frowned upon if not explicitly forbidden in corporate environments.”
    Actually Instant Messengers are not forbidden here. They are used all the time to communicate with colleagues within and outside to the company.

    And yes, the trick is slightly overkill, but it worked for me.

  5. A common trick that works for non-shared hosts. Most content filters don’t block by IP simply because so many sites are using shared hosting plans, so blocking by IP leads to lots of incorrect blocks.

    If the site provides SSL, you can use that to get around content filters as well.

    And finally, if your company uses a blacklisting service (the school I work for uses SonicWall) they often times mis-categorize sites. Find the support page where you can request a re-categorization, and submit the blocked site.

    I’ve gotten numerous open source blogs switched from “Games” (blocked) to “IT” (not blocked) this way.

    Happy hacking! 🙂

  6. And why a traceroute?? I think a ping should be enough to get the target ip. But this is a problem for countries with censored internet like the uae. In these countries it is not allowed to use a IP number instead the DNS Name.

  7. I have that problem here, my Co worker doesn’t work I wish they’d get rid of him but they are trying to get us better benifits and pay. I blocked alot of sites he goes to (they aren’t suitable for the school district either) and he has recently turned to using the IP address to get to them. Bad for him is I’m not stupid and I read the logs, any site that comes up via IP I look and and block the IP. If this were a proper business each attempt at getting around it would be reported and eventually the person fired but meh.

    I’m just griping I guess, at least I’m unfiltered and we don’t block sourceforge so I can get gimp sharp win 11 and the futures 🙂

  8. I’m on the other side of the fence here, as it’s part of my job to stop users from doing exactly that.

    So thanks for the hint on how to close this down 🙂

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